Various types of wooden shakes and shingles are known and these are usually produced from a log block by splitting or sawing tapered board pieces from the block. Other shakes are produced by end splitting a board piece of substantially uniform thickness from the log block and then sawing the board piece at an angle whereby to produce tapered shakes, which in this case, have an uneven surface created by the grain of the wood when it is split and the other surface is a flat sawn surface. Other shakes are produced wherein both sides of the shake have an uneven surface by splitting the block, end-for-end, at an angle. This process is largely a manual process. Other shakes (tapersawn shakes) are produced by sawing tapered pieces from a log block thereby creating a tapered shake with both sides flatsawn. In fact, the manufacturing of shakes is greatly a manual process and includes manual classification of several different types and grades.
Split shakes are distinguished from shingles in that they are of substantially constant thickness, with at least one split surface 3/8" to 3/4" thick, and cut in lengths of 18 inches or 24 inches. The best shakes are usually produced from clear heartwood log blocks which can produce 100 percent edgegrain with no defects. The shake is split from a log block with the split oriented at an angle of approximately 45 degrees or more to annual rings so that the surface of the shake has an edge or vertical grain which creates an elongated ripple effect throughout and extending longitudinally of the shake. This ripple effect surface is pleasing to the eye when a roof or wall is cladded with the shakes. Some other types of shakes permit the inclusion of flatgrain which is caused when the rings form an angle of less than 45 degrees with the surface of the shake. Flatgrain was proven to be less durable than edgegrain when exposed to the weather. Furthermore, when a roof or wall is constructed with shakes, the exposed surface of each course of shakes can be made greater than with shingles. When splitting a log block to form a shake, the cut shake will follow some grain divergence and generally will not be of a uniform constant plane thereacross and may have some curvature therein. Split shakes are graded on their best split face. Tapersawn shakes and shingles are graded from the best face. Premium grade shakes are usually free of manufacturing defects such as shims and feather tips and should be 100 percent clear heartwood and 100 percent edgegrain.
When shakes are split from log blocks, often these may have a curvature therein due to the direction of the grain. In order to produce good quality premium and No. 1 grade split shakes, it is very important to select top grade logs and this demand has escalated the cost of these logs. Only log blocks with very fine wood grain can split straight and because of the shrinking raw material supply it has become more difficult to get the type and quality of raw material that will split properly
The classification and grading of shingles by wood grain and other natural or machine defects is a difficult one as the operator must quickly, within a split second, identify the type of grain of the product produced, be it cross grain, diagonal grain, edge vertical grain, flat grain, or mixed grain. Accordingly, with so many classifications, it can be appreciated that it is extremely difficult to obtain accurate classification and often, to eliminate errors the classification may be repeated in the production line.
It can therefore be appreciated that shingles and split shakes are costly materials due to the fact that they are labour intensive to produce and utilize high quality selected logs that are capable of being split substantially uniformly from log pieces that are cut in block form. It can be appreciated that these methods of fabrication result in substantial material waste. Also, old growth fine grained logs are becoming more and more difficult to find and its cost escalation is also the result of over exploitation. There is therefore a need to produce a shake from poorer grade logs which are not heartwood and which may have imperfections and knots which restrict the manufacture of split shake products. A method of manufacture which is less labour intensive and less costly would be desirable.